hasNextBlock

确定分块文件集是否有其他分块

自 R2020a 起

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语法

tf = hasNextBlock(bs)

说明

示例

如果在 bs 指定的 BlockedFileSet 对象中有另一个分块可供处理，则 tf = hasNextBlock(bs) 返回逻辑值 1 (true)。否则，将返回逻辑值 0 (false)。

示例

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检查分块文件集是否有其他分块

打开实时脚本

检查分块文件集是否有其他分块可供处理，并以迭代方式读取数据。

为一组文件创建一个分块文件集 bs。

folder = {'accidents.mat','airlineResults.mat','census.mat','earth.mat'}

folder = 1x4 cell
    {'accidents.mat'}    {'airlineResults.mat'}    {'census.mat'}    {'earth.mat'}

bs = matlab.io.datastore.BlockedFileSet(folder)

bs = 
  BlockedFileSet with properties:

                   NumBlocks: 4
               NumBlocksRead: 0
                   BlockSize: 'file'
                   BlockInfo: BlockInfo for all 4 blocks
    AlternateFileSystemRoots: {}

使用 hasNextBlock 和 nextblock 函数，一次读取一个分块的分块信息，同时分块仍保留在文件集中。

while hasNextBlock(bs)
   file = nextblock(bs)
end

file = 
  1x1 BlockInfo
                                                    Filename                                                    FileSize    Offset    BlockSize
    ________________________________________________________________________________________________________    ________    ______    _________

    "/mathworks/devel/bat/filer/batfs1904-0/Bdoc24a.2528353/build/matlab/toolbox/matlab/demos/accidents.mat"      7343        0         7343

file = 
  1x1 BlockInfo
                                      Filename                                        FileSize     Offset    BlockSize 
    _____________________________________________________________________________    __________    ______    __________

    "/tmp/Bdoc24a_2528353_989294/tpe9f9016d/matlab-ex12893120/airlineResults.mat"    1.5042e+05      0       1.5042e+05

file = 
  1x1 BlockInfo
                                                  Filename                                                   FileSize    Offset    BlockSize
    _____________________________________________________________________________________________________    ________    ______    _________

    "/mathworks/devel/bat/filer/batfs1904-0/Bdoc24a.2528353/build/matlab/toolbox/matlab/demos/census.mat"      353         0          353

file = 
  1x1 BlockInfo
                                                  Filename                                                  FileSize    Offset    BlockSize
    ____________________________________________________________________________________________________    ________    ______    _________

    "/mathworks/devel/bat/filer/batfs1904-0/Bdoc24a.2528353/build/matlab/toolbox/matlab/demos/earth.mat"     32522        0         32522